ArangoDB v3.8 reached End of Life (EOL) and is no longer supported.
This documentation is outdated. Please see the most recent version at docs.arangodb.com
Transactions are executed until there is either a rollback or a commit. On rollback the operations from the transaction will be reversed.
The RocksDB storage engine applies operations of a transaction in main memory only until they are committed. In case of an a rollback the entire transaction is just cleared, no extra rollback steps are required.
In the event of a server-crash the storage engine will scan the write-ahead log to restore certain meta-data like the number of documents in collection or the selectivity estimates of secondary indexes.